16S Ribosomal DNA-based Analysis of Bacteria in Shrimp Sauce: Effect of Fermentation Temperature on Protease System and Product Quality
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Abstract:
Changes in the bacterial flora and the protease system in shrimp sauce at different fermentation temperatures were analyzed using 16S ribosomal DNA (rDNA) high-throughput sequencing and zymography methods, respectively. The role of bacteria in the fermentation of shrimp sauce was examined by measuring various quality indicators. The results showed that the bacteria count were significantly higher than that of fungi, indicating the important contribution of bacteria to the fermentation of shrimp sauce. The bacterial flora in shrimp sauce was very complex and showed significant differences at different temperatures. The bacterial flora and protease system underwent dynamic changes during fermentation. At 25 ℃ and 35 ℃, fewer proteases were deactivated and a large number of flavor-forming bacteria were detected, including Tetragenococcus and Virgibacillus. However, at 45 ℃, severe protease inactivation was observed and the detected bacteria were not related to flavor formation. Additionally, sensory evaluation showed the lowest values in these groups. Therefore, 45 ℃ is not a suitable temperature for the fermentation of shrimp sauce. The contents of amino nitrogen, saltless soluble solids, and total volatile base nitrogen (TVN-N) and trimethylamine (TMA) reached the maximum values after 30 days of fermentation, and then generally remained constant. However, there were significant changes in the bacterial flora; one novel protease was detected, and the flavor of shrimp sauce continued to improve.
